This invention relates to closures for containers, and more particularly relates to a safety closure for a container which holds potentially dangerous products, such as drugs, cleaning solutions, caustics, volatile liquids and the like. In recent years Government regulations and public concern are requiring more and more of these products to be packaged in containers that are resistant to being opened by children. At the same time, the containers must be relatively simple to be opened by adults. Otherwise, the object of the regulations would be defeated, since a container that is too difficult to open or reclose by an adult would be frequently left open by adults. Moreover, it is desirable in containers to have some means for insuring that the closure or cap is not over-tightened or under-tightened during use, and also, some means for preventing accidental loosening of the cap during handling, shipping or storage is desired.
In the prior art various attempts have been made to solve the above problems and provide a closure which meets the requirements of the law. Such closures are exemplified, for example, in U.S. Pat. Nos. 3,841,514, 3,891,110 and 3,939,788. In U.S. Pat. No. 3,841,514 the closure is constructed to be squeezed on diametrically opposite sides thereof to release latching or locking lugs on the closure and container. U.S. Pat. No. 3,891,110 discloses a closure having a yieldable seal means in the end thereof which engages the end of the container and an outwardly directed annular flange is on the bottom edge of the closure and has a plurality of lugs thereon for cooperation with interengaging structure on the container, whereby the closure may be threaded onto the container and latching or locking will be effected between the closure and container by cooperation between the lugs thereon. The lugs include a plurality of circumferentially spaced lugs to insure that the closure will be locked even though the rotational position thereof on the container may be different from other closures on like containers. U.S. Pat. No. 3,939,788 discloses a device wherein a pair of opposite wing members are secured on the neck of the container with lug means thereon for cooperation with lugs or recesses inside an enlarged skirt portion of the cap or closure. In operation of this closure it is necessary to simultaneously pull both wings downwardly in order to release the interengaging detents to release the cap.
The present invention solves the problems found in the prior art devices by providing a closure cap of relatively rigid material which cooperates with a threaded neck on a container in a manner whereby the closure is in substantially the same circumferential position every time it is threaded fully onto the threaded neck, and a flexible collar on the neck cooperates with detent means on the bottom edge of the cap to make the cap child resistant and yet enables it to be opened relatively easily by an adult. Moreover, the cap is not likely to accidentially be loosened during handling, storing and shipping and it is economical to manufacture, since expensive modifications to existing machinery and dies will not be necessary. Moreover, the invention may be applied to either a plastic, metal or glass container and may even be utilized on a container having an internally threaded neck.